package com.rhythm.commons.collections;

import java.util.Iterator;

/**
 * An iterator that supports a one-element lookahead while iterating.
 */
public interface PeekingIterator<E> extends Iterator<E> {

  /**
   * Returns the next element in the iteration without advancing the iteration.
   *
   *<p> If possible, calls to {@code peek()} should not affect the iteration.
   * As is the case with most Iterators, modifications to the underlying
   * iteration may have unanticipated results.
   *</p>
   * <p>If there are no remaining elements in the iteration, {@code peek()}
   * will throw a {@code NoSuchElementException}.  (A {@code null} return value
   * does <em>not</em> indicate that this iterator has reached the end of its
   * iteration.)
   *</p>
   * <p><b>Usage note</b>:  Implementations may, but are not required to,
   * support {@code remove()} following a call to {@code peek()}.
   *</p>
   * @throws java.util.NoSuchElementException if the iteration has
   *     no more elements.
   */
  E peek();
}
